<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src = "./jquery-1.6.2.min.js"></script>
</head>
<style>
    div{
        background-color: rgb(143, 37, 214);
    }
</style>
<body>
    <div id="a">test</div>
    <script>
        //$('div').css({width:'200px',height:'200px'});
        $(document).ready(function() {
            $('#a').css({
           'width': '200px',
          'height': '200px'
          });
          });
    </script>
</body>
</html>